U.S. patent application number 14/499224 was filed with the patent office on 2015-08-13 for front light module and electronic paper display device having the same.
The applicant listed for this patent is E Ink Holdings Inc.. Invention is credited to Lin-An CHEN, Yun-Nan HSIEH, Cheng-Hsien LIN.
Application Number | 20150226906 14/499224 |
Document ID | / |
Family ID | 53774792 |
Filed Date | 2015-08-13 |
United States Patent
Application |
20150226906 |
Kind Code |
A1 |
HSIEH; Yun-Nan ; et
al. |
August 13, 2015 |
FRONT LIGHT MODULE AND ELECTRONIC PAPER DISPLAY DEVICE HAVING THE
SAME
Abstract
The front light module includes a light guide plate, a light
source, a first light transmissive substrate, a second light
transmissive substrate, and a printing ink layer. The light guide
plate has a first light emitting surface, a second light emitting
surface, and a light incident surface. The light source faces the
light incident surface. The first light transmissive substrate is
located on the first light emitting surface. The second light
transmissive substrate is located on the surface of the first light
transmissive substrate facing away from the light guide plate, and
the thickness of the second light transmissive substrate is smaller
than that of the first light transmissive substrate. The printing
ink layer is located on the surface of the second light
transmissive substrate facing the first light transmissive
substrate, and on an edge of the second light transmissive
substrate.
Inventors: |
HSIEH; Yun-Nan; (HSINCHU,
TW) ; LIN; Cheng-Hsien; (HSINCHU, TW) ; CHEN;
Lin-An; (HSINCHU, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
E Ink Holdings Inc. |
Hsinchu |
|
TW |
|
|
Family ID: |
53774792 |
Appl. No.: |
14/499224 |
Filed: |
September 28, 2014 |
Current U.S.
Class: |
359/296 ;
362/603 |
Current CPC
Class: |
G02F 1/1677 20190101;
G02F 1/167 20130101; G02B 6/006 20130101; G02B 6/0065 20130101;
G02B 6/005 20130101; G02B 6/0043 20130101; G02F 1/1336 20130101;
G02F 2001/133616 20130101 |
International
Class: |
F21V 8/00 20060101
F21V008/00; G02F 1/1335 20060101 G02F001/1335; G02F 1/167 20060101
G02F001/167 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2014 |
TW |
103104618 |
Claims
1. A front light module for a display device, comprising: a light
guide plate having a first light emitting surface, a second light
emitting surface opposite to the first light emitting surface, and
a light incident surface between the first and second light
emitting surfaces; a light source facing the light incident surface
of the light guide plate; a first light transmissive substrate
located on the first light emitting surface of the light guide
plate; a second light transmissive substrate located on a surface
of the first light transmissive substrate facing away from the
light guide plate, wherein a thickness of the second light
transmissive substrate s smaller than a thickness of the first
light transmissive substrate; and a printing ink layer located on a
surface of the second light transmissive substrate facing the first
light transmissive substrate, wherein the printing ink layer is
located on an edge of the second light transmissive substrate.
2. The front light module of claim 1, further comprising: a first
adhesion layer between the light guide plate and the first light
transmissive substrate.
3. The front light module of claim 1, further comprising: a second
adhesion layer between the first and second light transmissive
substrates, such that the second light transmissive substrate and
the printing ink layer are adhered to the first light transmissive
substrate.
4. The front light module of claim 3, wherein a total thickness of
the second light transmissive substrate and the printing ink layer
is in a range from 1% to 25% of a total thickness of the first
light transmissive substrate, the second adhesion layer, the
printing ink layer, and the second light transmissive
substrate.
5. The front light module of claim 3, further comprising: an
overcoat layer covering the printing ink layer and a surface of the
second light transmissive substrate facing the first light
transmissive substrate, wherein the second adhesion layer is
between the overcoat layer and the first light transmissive
substrate.
6. The front light module of claim 5, wherein a total thickness of
the second light transmissive substrate and the printing ink layer
is in a range from 1% to 25% of a total thickness of the first
light transmissive substrate, the second adhesion layer, the
overcoat layer, the printing ink layer, and the second light
transmissive substrate.
7. The front light module of claim 1, wherein the first light
transmissive substrate is made of a material comprising one of
polycarbonate, polymethyl methacrylate, glass, and a combination
thereof.
8. The front light module of claim 1, wherein the second light
transmissive substrate is made of a material comprising
polyethylene terephthalate.
9. The front light module of claim 1, wherein a thickness of the
first light transmissive substrate is in a range from 0.4 to 1.2
mm.
10. The front light module of claim 1, wherein a thickness of the
second light transmissive substrate is in a range from 0.1 to 0.2
mm.
11. An electronic paper display device comprising: a display module
comprising: a driving array substrate; and a front panel laminate
located on the driving array substrate and the front panel laminate
comprising a protection substrate and a display medium layer,
wherein the display medium layer is between the driving array
substrate and the protection substrate; and a front light module
located on the display module and the front light module
comprising: a light guide plate having a first light emitting
surface, a second light emitting surface opposite to the first
light emitting surface, and a light incident surface between the
first and second light emitting surfaces, wherein the second light
emitting surface is located on the display module; a light source
facing the light incident surface of the light guide plate; a first
light transmissive substrate located on the first light emitting
surface of the light guide plate; a second light transmissive
substrate located on a surface of the first light transmissive
substrate facing away from the light guide plate, wherein a
thickness of the second light transmissive substrate is smaller
than a thickness of the first light transmissive substrate; and a
printing ink layer located on a surface of the second light
transmissive substrate facing the first light transmissive
substrate, wherein the printing ink layer is located on an edge of
the second light transmissive substrate.
12. The electronic paper display device of claim 11, wherein the
front light module further comprises: a first adhesion layer
between the light guide plate and the first light transmissive
substrate.
13. The electronic paper display device of claim 11, wherein the
front light module further comprises: a second adhesion layer
between the first and second light transmissive substrates, such
that the second light transmissive substrate and the printing ink
layer are adhered to the first light transmissive substrate.
14. The electronic paper display device of claim 13, wherein a
total thickness of the second light transmissive substrate and the
printing ink layer is in a range from 1% to 25% of a total
thickness of the first light transmissive substrate, the second
adhesion layer, the printing ink layer, and the second light
transmissive substrate.
15. The electronic paper display device of claim 13, wherein the
front light module further comprises: an overcoat layer covering
the printing ink layer and a surface of the second light
transmissive substrate facing the first light transmissive
substrate, wherein the second adhesion layer is between the
overcoat layer and the first light transmissive substrate.
16. The electronic paper display device of claim 15, wherein a
total thickness of the second light transmissive substrate and the
printing ink layer is in a range from 1% to 25% of a total
thickness of the first light transmissive substrate, the second
adhesion layer, the overcoat layer, the printing ink layer, and the
second light transmissive substrate.
17. The electronic paper display device of claim 11, wherein the
first light transmissive substrate is made of a material comprising
one of polycarbonate, polymethyl methacrylate, glass, and a
combination thereof.
18. The electronic paper display device of claim 11, wherein the
second light transmissive substrate is made of a material
comprising polyethylene terephthalate.
19. The electronic paper display device of claim 11, wherein a
thickness of the first light transmissive substrate is in a range
from 0.4 to 1.2 mm.
20. The electronic paper display device of claim 11, wherein a
thickness of the second light transmissive substrate is in a range
from 0.1 to 0.2 mm.
Description
RELATED APPLICATIONS
[0001] This application claims priority to Taiwanese Application
Serial Number 103104618, filed Feb. 12, 2014, which is herein
incorporated by reference.
BACKGROUND
[0002] 1. Field of Invention
[0003] The present invention relates to a front light module and an
electronic paper display device.
[0004] 2. Description of Related Art
[0005] In the market full of a wide variety of consumer electronic
products, portable electronic devices, e.g. an electronic book, now
have extensively utilized electronic paper display devices as
display screens. A display medium layer (also referred to as an
electronic ink) of an electronic paper display device is mainly
made of an electrophoresis buffer and white and black charged
particles doped in the electrophoresis buffer. The white and black
charged particles are movable driven by applying a voltage to the
display medium layer, so as to present individual pixel with black,
white or a gray level.
[0006] In the present technology, the electronic paper display
device utilizes an incident light that irradiates the display
medium layer to achieve the purpose of display. Therefore, the
electronic paper display device needs no backlight, which reduces
the power consumption of the electronic paper display device. In
order to expand the application of the electronic paper display
device, a front light module is often arranged above the front
panel laminate of the electronic paper display device. Even if the
electronic paper display device is used in a place with
insufficient ambient light, the front light module may emit an
incident light to the display medium layer. As such, users can see
the images displayed by the electronic paper display device.
[0007] The conventional front light module of the electronic paper
display device may consist of a light source, a light guide plate,
and a light transmissive protection cover having an ink layer
printed thereon. The surface of the light transmissive protection
cover having the ink layer is adhered to the light guide plate. The
ink layer is printed on the edge of the light transmissive
protection cover to be a frame for shielding light. However, the
light emitted by the light source is guided to the external surface
of the light transmissive protection cover. The perpendicular
distance between the external surface of the light transmissive
protection cover and the ink layer is so far that the light is apt
to be reflected to the ink layer by the external surface of the
light transmissive protection cover, resulting in and the
fluorescent illumination and visual interference. In this regard,
only a dark (e.g., black) ink layer is optional to reduce the
influence of the fluorescent illumination. The limitation in
choosing the colors of the ink layer restricts the change in the
color of the housing of the electronic paper display device. On the
other hand, an additional air gap may be used to change the
refraction direction of the light, which however scarifies the
transmittance of the front light module.
SUMMARY
[0008] An aspect of the present invention is to provide a front
light module used in a display device.
[0009] According to an embodiment of the present invention, a front
light module includes a light guide plate, a light source, a first
light transmissive substrate, a second light transmissive
substrate, and a printing ink layer. The light guide plate has a
first light emitting surface, a second light emitting surface
opposite to the first light emitting surface, and a light incident
surface between the first and second light emitting surfaces. The
light source faces the light incident surface of the light guide
plate. The first light transmissive substrate is located on the
first light emitting surface of the light guide plate. The second
light transmissive substrate is located on the surface of the first
light transmissive substrate facing away from the light guide
plate. The thickness of the second light transmissive substrate is
smaller than the thickness of the first light transmissive
substrate. The printing ink layer is located on the surface of the
second light transmissive substrate facing the first light
transmissive substrate, and on the edge of the second light
transmissive substrate.
[0010] In one embodiment of the present invention, the front light
module further includes a first adhesion layer. The first adhesion
layer is between the light guide plate and the first light
transmissive substrate.
[0011] In one embodiment of the present invention, the front light
module further includes a second adhesion layer. The second
adhesion layer is between the first and second light transmissive
substrates, such that the second light transmissive substrate and
the printing ink layer are adhered to the first light transmissive
substrate.
[0012] In one embodiment of the present invention, the total
thickness of the second light transmissive substrate and the
printing ink layer is in a range from 1% to 25% of the total
thickness of the first light transmissive substrate, the second
adhesion layer, the printing ink layer, and the second light
transmissive substrate.
[0013] In one embodiment of the present invention, the front light
module further includes an overcoat layer. The overcoat layer
covers the printing ink layer and the surface of the second light
transmissive substrate facing the first light transmissive
substrate. The second adhesion layer is between the overcoat layer
and the first light transmissive substrate.
[0014] In one embodiment of the present invention, the total
thickness of the second light transmissive substrate and the
printing ink layer is in a range from 1% to 25% of the total
thickness of the first light transmissive substrate, the second
adhesion layer, the overcoat layer, the printing ink layer, and the
second light transmissive substrate.
[0015] In one embodiment of the present invention, the first light
transmissive substrate is made of a material comprising one of
polycarbonate, polymethyl methacrylate, glass, and a combination
thereof.
[0016] In one embodiment of the present invention, the second light
transmissive substrate is made of a material including polyethylene
terephthalate.
[0017] In one embodiment of the present invention, the thickness of
the first light transmissive substrate is in a range from 0.4 to
1.2 mm.
[0018] In one embodiment of the present invention, the thickness of
the second light transmissive substrate is in a range from 0.1 to
0.2 mm.
[0019] Another aspect of the present invention is to provide an
electronic paper display device.
[0020] According to an embodiment of the present invention, an
electronic paper display device includes a display module and a
front light module. The display module includes a driving array
substrate and a front panel laminate. The front panel laminate is
located on the driving array substrate and includes a protection
substrate and a display medium layer. The display medium layer is
between the driving array substrate and the protection substrate.
The front light module is located on the display module and
includes a light guide plate, a light source, a first light
transmissive substrate, a second light transmissive substrate, and
a printing ink. The light guide plate has a first light emitting
surface, a second light emitting surface opposite to the first
light emitting surface, and a light incident surface between the
first and second light emitting surfaces. The second light emitting
surface is located on the display module. The light source faces
the light incident surface of the light guide plate. The first
light transmissive substrate is located on the first light emitting
surface of the light guide plate. The second light transmissive
substrate is located on the surface of the first light transmissive
substrate facing away from the light guide plate. The thickness of
the second light transmissive substrate is smaller than the
thickness of the first light transmissive substrate. The printing
ink layer is located on the surface of the second light
transmissive substrate facing the first light transmissive
substrate, and on the edge of the second light transmissive
substrate.
[0021] In the aforementioned embodiments of the present invention,
the front light module has the first and second light transmissive
substrates, and the first light transmissive substrate may provide
a supporting force for the front light module. Therefore, the
thickness of the second light transmissive substrate may be
reduced. As a result, the perpendicular distance between the
printing ink on the second transmissive substrate and the surface
of the second transmissive substrate facing away from the first
transmissive substrate may be reduced, such that the light is not
easily reflected to the printing ink by the second transmissive
substrate. Therefore, when the front light module of the present
invention is in use, fluorescent light is not easily apt to be
found above the printing ink layer, such that the disturbance of
the sense of sight may be prevented. Moreover, the printing ink
layer with a dark color (e.g., a black color) or a light color
(e.g., a white color) may be selectively used in the front light
module to correspond to the appearance design (e.g., the housing
color) of the electronic paper display device, such that the color
of the printing ink layer is in an adjustable manner.
[0022] It is to be understood that both the foregoing general
description and the following detailed description are by examples,
and are intended to provide further explanation of the invention as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The invention can be more fully understood by reading the
following detailed description of the embodiments, with reference
made to the accompanying drawings as follows.
[0024] FIG. 1 is a top view of an electronic paper display device
according to an embodiment of the present invention;
[0025] FIG. 2 is a cross-sectional view of the electronic paper
display device taken along line 2-2 shown in FIG. 1;
[0026] FIG. 3 is a schematic view of a light source shown in FIG. 2
when the light. source emits light; and
[0027] FIG. 4 is a cross-sectional view of a front light module
according to an embodiment of the present invention.
DETAILED DESCRIPTION
[0028] Reference will now be made in detail to the present
embodiments of the invention, examples of which are illustrated in
the accompanying drawings. Wherever possible, the same reference
numbers are used in the drawings and the description to refer to
the same or like parts.
[0029] FIG. 1 is a top view of an electronic paper display device
200 according to an embodiment of the present invention. FIG. 2 is
a cross-sectional view of the electronic paper display device 200
taken along line 2-2 shown in FIG. 1. As shown in FIG. 1 and FIG.
2, the electronic paper display device 200 includes a display
module 210 and a front light module 100. The front light module 100
is located on the display module 210 and includes a light guide
plate 110, a light source 120, a first light transmissive substrate
130, a second light transmissive substrate 140, and a printing ink
layer 150. The light guide plate 110 has a first light emitting
surface 112, a second light emitting surface 114 opposite to the
first light emitting surface 112, and a light incident surface 116
between the first and second light emitting surfaces 112, 114. The
light source 120 is adjacent to and faces the light incident
surface 116 of the light guide plate 110. The first light
transmissive substrate 130 is located on the first light emitting
surface 112 of the light guide plate 110 and has opposite surfaces
132, 134. The second light transmissive substrate 140 is located on
the surface 134 of the first light transmissive substrate 130
facing away from the light guide plate 110. The second light
transmissive substrate 140 has opposite surfaces 142, 144.
[0030] In this embodiment, the printing ink layer 150 is located on
the surface 142 of the second light transmissive substrate 140
facing the first light transmissive substrate 130. The printing ink
layer 150 is located on the edge of the second light transmissive
substrate 140 to be as a frame for shielding light, such that the
display area 202 of the electronic paper display device 200 (i.e.,
the inner area of the dotted line shown in FIG. 1) may be defined
by the printing ink layer 150. The pattern of the aforesaid
printing ink layer 150 may be other irregular pattern or include
plural patterns with different colors for broadening the
application of the printing ink layer 150. For example, the
printing ink layer 150 may be a logo or an aesthetic pattern with
different colors.
[0031] The front light module 100 has the first and second light
transmissive substrates 130, 140, and the first light transmissive
substrate 130 may provide a supporting force for the front light
module 100 and protect the light guide plate 110. Therefore, the
thickness D1 of the second light transmissive substrate 140 may be
reduced, such that the thickness D1 of the second light
transmissive substrate 140 may be smaller than the thickness D2 of
the first light transmissive substrate 130. As a result, the
perpendicular distance between the printing ink layer 150 on the
second transmissive substrate 140 and the surface 144 of the second
transmissive substrate 140 (i.e., the thickness D1) may be
reduced.
[0032] In this embodiment, the front light module 100 further
includes a first adhesion layer 160 and a second adhesion layer
170. The first adhesion layer 160 is between the light guide plate
110 and the first light transmissive substrate 130, such that the
first light transmissive substrate 130 is adhered to the light
guide plate 110. The second adhesion layer 170 is between the first
and second light transmissive substrates 130, 140, such that the
second light transmissive substrate 140 and the printing ink layer
150 are adhered to the first light transmissive substrate 130. The
total thickness D3 of the second light transmissive substrate 140
and the printing ink layer 150 is in a range from 1% to 25% of the
total thickness D4 of the first light transmissive substrate 130,
the second adhesion layer 170, the printing ink layer 150, and the
second light transmissive substrate 140.
[0033] When the front light module 100 is manufactured, the
printing ink layer 150 may be printed on the surface 142 of the
second light transmissive substrate 140, and subsequently the first
light transmissive substrate 130 may be adhered to the light guide
plate 110 by the first adhesion layer 160. Finally, the second
light transmissive substrate 140 having the printing ink layer 150
may be adhered to the surface 134 of the first light transmissive
substrate 130 by the second adhesion layer 170.
[0034] However, the aforesaid sequence does not limit the present
invention. For example, the second light transmissive substrate 140
having the printing ink layer 150 may be adhered to the surface 134
of the first light transmissive substrate 130 by the second
adhesion layer 170, and subsequently the first light transmissive
substrate 130 is adhered to the light guide plate 110 by the first
adhesion layer 160.
[0035] In this embodiment, the first light transmissive substrate
130 may be made of a material comprising polycarbonate (PC),
polymethyl methacrylate (PMMA), glass, or a combination thereof,
and the thickness D2 of the first light transmissive substrate 130
may be in a range from 0.4 to 1.2 mm. The second light transmissive
substrate 140 may be made of a material including polyethylene
terephthalate (PET), and the thickness D1 of the second light
transmissive substrate 140 may be in a range from 0.1 to 0.2 mm.
When the thickness D2 of the first light transmissive substrate 130
is increasingly thicker, the thickness difference between the
thickness D2 of the first light transmissive substrate 130 and the
thickness D1 of the second light transmissive substrate 140 is
larger, such that the utility of reducing the fluorescent light
that generates above the printing ink layer 150 is increasingly
more obvious.
[0036] The display module 210 includes a driving array substrate
220 and a front panel laminate 230. The front panel laminate 230 is
located on the driving array substrate 220. The front panel
laminate 230 includes a protection substrate 232 and a display
medium layer 234. The display medium layer 234 is between the
driving array substrate 220 and the protection substrate 232. The
second light emitting surface 114 of the light guide plate 110 is
located on the display module 210. Moreover, the front light module
100 is used in the display device 200, but the present invention is
not limited in this regard, other display modules that need front
light may also utilize the front light module 100.
[0037] In the following description, the state of the light in the
display device 200 when the light source 120 emits light will be
described.
[0038] FIG. 3 is a schematic view of the light source 120 shown in
FIG. 2 when the light source 120 emits light. As shown in FIG. 3,
when the light source 120 emits light, the light L1 may pass
outward the first light emitting surface 112 of the light guide
plate 110, and the light L2 may pass outward the second light
emitting surface 114 of the light guide plate 110. The thickness D1
of the second light transmissive substrate 140 is small. For
example, the total thickness D3 of the second light transmissive
substrate 140 and the printing ink layer 150 is 20% of the total
thickness D4 of the first light transmissive substrate 130, the
second adhesion layer 170, the printing ink layer 150, and the
second light transmissive substrate 140. Therefore, the light L1 is
not easily reflected to the printing ink layer 150 by the second
light transmissive substrate 140. As a result, when the front light
module 100 is in use, fluorescent light is not easily apt to be
found above the printing ink layer 150, such that the image of the
display area 202 (see. FIG. 1) does not suffer the disturbance of
the sense of sight caused by the fluorescent light of the printing
ink layer 150. That is to say, an additional air gap does not need
to be used in the front light module 100 to reduce the light L1
reflected to the printing ink layer 150. Therefore, the
transmittance of the front light module 100 may be improved.
[0039] Moreover, since the front light module 100 may reduce the
light L1 reflected to the printing ink layer 150, designers may
selectively use the printing ink layer 150 with a dark color (e.g.
a black color) or a light color (e.g., a white color) to correspond
to the appearance design (e.g., the housing color) of the
electronic paper display device 200. As a result, the color of the
printing ink layer 150 is in an adjustable manner.
[0040] In this embodiment, the display medium layer 234 includes
plural microencapsules 236. Each of the microencapsules 236
includes plural dark electrophoretic particles 237 and plural
electrophoretic particles 238. When the light source 120 emits
light, the light L2 emitted from the second light emitting surface
114 of the light guide plate 110 may enter the display medium layer
234. When the bright electrophoretic particles 238 are near the
upper side of the microencapsules 236, and the dark electrophoretic
particles 237 are near the lower side of the microencapsules 236,
the display module 210 can reflect the light L2 so as to display as
a bright surface in the area of the microencapsules 236. On the
other hand, when the bright electrophoretic particles 238 are near
the lower side of the microencapsules 236, and the dark
electrophoretic particles 237 are near the upper side of the
microencapsules 236, the display module 210 does not reflect the
light L2 so as to display as a dark surface in the area of the
microencapsules 236.
[0041] It is to be noted that the connection relationships and the
materials of the elements described above will not be repeated in
the following description. In the following description, other
types of the front light module will be described.
[0042] FIG. 4 is a cross-sectional view of a front light module
100a according to an embodiment of the present invention. As shown
in FIG. 4 the front light module 100a includes the light guide
plate 110, the light source 120, the first light transmissive
substrate 130, the second light transmissive substrate 140, and the
printing ink layer 150. The difference between this embodiment and
the embodiment show in FIG. 2 is that the front light module 100a
further includes an overcoat (OC) layer 180. The overcoat layer 180
covers the printing ink layer 150 and the surface 142 of the second
light transmissive substrate 140 facing the first light
transmissive substrate 130, and the second adhesion layer 170 is
between the overcoat layer 180 and the first light transmissive
substrate 130. The overcoat layer 180 may be made of a material
including ultraviolet curable material, but the present invention
is not limited in this regard.
[0043] In this embodiment, the total thickness D3 of the second
light transmissive substrate 140 and the printing ink layer 150 is
in a range from 1% to 25% of the total thickness D5 of the first
light transmissive substrate 130, the second adhesion layer 170,
the overcoat layer 180, the printing ink layer 150, and the second
light transmissive substrate 140.
[0044] Although the present invention has been described in
considerable detail with reference to certain embodiments thereof,
other embodiments are possible. Therefore, the spirit and scope of
the appended claims should not be limited to the description of the
embodiments contained herein.
[0045] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
present invention without departing from the scope or spirit of the
invention. In view of the foregoing, it is intended that the
present invention cover modifications and variations of this
invention provided they fall within the scope of the following
claims.
* * * * *